Question

why do ice float on water

Answer 1

Because ice is less dense than water

Answer 2

Ice floats because it is about 9% less dense than liquid water. In other words, ice takes up about 9% more space than water, so a liter of ice weighs less than a liter water. The heavier water displaces the lighter ice, so ice floats to the top. One consequence of this is that lakes and rivers freeze from top to bottom, allowing fish to survive even when the surface of a lake has frozen over. If ice sank, the water would be displaced to the top and exposed to the colder temperature, forcing rivers and lakes to fill with ice and freeze solid.

Answer 3

if you want details on the molecular reason it floats, ice has hydrogen bonds that from in the shape of rings giving the shape of a crystal and making it have space between molecules unlike liquid water therefore making it less dense
this is also why water expands when freezing

Answer 4

hope this helps https://www.boundless.com/biology/properties-of-water/four-important-properties-of-water/ice-floats-on-water/